<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
    <!--引入css-->
    <link rel="stylesheet" href="my.css">
</head>
<body>
<!--内联-->
<h1 style="color: #d7faf0">内联样式1</h1>
<h1 style="color:red">内联样式1</h1>
<!--内部-->
<style>
    h2{color: aqua}
</style>

<h2>内部样式1</h2>
<h2>内部样式2</h2>
<h3>外部样式</h3>
<h3>外部样式</h3>
</body>
</html>